1. Field of the Invention
This invention generally relates to the field of distributed recognition system. More particularly, the presented invention relates to a configurable distributed speech recognition system.
2. Description of the Prior Art
Today, the field of speech recognition has a vision due to the advancement and development of wireless communication product. Wireless Mobile Device (WMD) with the features of portability and mobility, always has limited speed and approach of data inputting. Therefore, it is very important to have a speech recognition technique to resolve this problem. However, implementing a satisfactory speech recognizer for public user requires powerful capability of computation and memory resource, also involves various types of databases for acoustics, pronunciation, grammar and so on. Accordingly, realizing a speech recognizer on wireless mobile devices becomes impracticable.
According to the foregoing issue, there are many international speech research institutes and wireless communication product manufacturers propose an architecture called Server-Client, allocating the resource of recognition process to server side and client side. The Aurora project of ETSI (European Telecommunications Standards Institute) is the largest leading project. The Aurora project proposes the “Distributed Speech Recognition, DSR” architecture as shown in FIG. 1.
However, the purpose of distributed speech recognition architecture is to resolve the low recognizing ratio of using mobile phone to Voice Portal system. So far, using mobile phone to request Voice Portal service usually causes poor recognition rate due to speech data transmitting problem. The reason is that the speech data encoding is designed for human hearing, thus, when few speech data loss during transmitting, it may not essentially effect human hearing, but it may damage the speech recognizer seriously.
For solving the foregoing problem, the Aurora project instead of using “Speech Channel” to transmit speech-encoded data, switches to use “Error Protected Data Channel” to transmit suitable speech parameter for recognizing. Besides, further distributing recognition computing is on both side of mobile phone (client) and Voice Portal (server). The main consideration is to use the resource of server, and reduce the effect caused by speech data transmitting error.
FIG. 1 shows the components of the Aurora architecture and future noise robust front-end standards for DSR applications. As shown in FIG. 1, the Aurora DSR architecture separates recognition process to Terminal DSR Front-End and Server DSR Back-End; thus the processing is distributed between the terminal and the network. The terminal performs the feature parameter extraction, or the front-end of the speech recognition system. These feature are transmitted over a data channel to a remote “back-end” recognizer. The end result is that the transmission channel has minimal impact on the recognition system performance and channel invariability is achieved. This performance advantage is good for DSR services provided for a particular network.
However, most of wireless mobile devices cannot provide enough capability to handle the required computation on the clients, accordingly, Aurora DSR architecture is not suitable for general wireless mobile device.
Therefore, it is needed to develop distributed speech recognition architecture for general wireless mobile devices. This architecture is allowed to be configured to achieve the optimal performance based on the given speaker profiles, environment conditions, the types of mobile device and the types of recognition services.